The field of the disclosure relates generally to direct current (DC) circuit protection systems and, more particularly, to a DC circuit breaker and a method of use thereof.
Many known power circuits utilize circuit breakers to detect over-currents and break the circuit in response. Known circuit breakers utilize a mechanical contactor to make and break the circuit between a line side and a load side. When broken by a mechanical contactor, the circuit breaker provides galvanic isolation between the line side and the load side by a physical separation of the conductive path. The physical separation is between contacts of the mechanical contactor and occurs within a medium, such as air, for example, or another dielectric material. Known circuit breakers also utilize solid state switches, although solid state switches do not provide the galvanic isolation provided by mechanical contactors. Consequently, current can leak through an open solid state switch. For this reason, among others, solid state switches alone often do not satisfy some electrical safety standards.
When breaking a circuit under load, which is to break the circuit while carrying a non-zero current, an arc can occur across the contacts of the mechanical contactor. Arcs can also occur when making the circuit under load. Arc prevention and suppression are important aspects of circuit breaker design. The arc itself is a low-impedance conductive path formed through the medium by ionization due in part to the electric field. Arcs are high-energy and can be damaging to components, especially to breaker contact surfaces. Arcs can be dangerous for people near the arc, and also to those relying on the disconnection of the circuit, because the arc delays the break of the circuit. Arcs can also create electromagnetic interference issues that present further safety concerns.
A known approach to arc prevention is to remove the load and, thus, the current before breaking or making the circuit. Known circuit breakers are designed to actuate the mechanical contactor with sufficient speed and force to interrupt the arc. In alternating current (AC) circuits, the speed and force necessary to interrupt the arc is low because the current alternates direction and passes through zero each cycle. In contrast, DC circuit breakers must interrupt a non-zero current, which makes arcs significantly more likely and requires greater speed and force. The likelihood of arcs in DC circuit breakers drives their costs up and generally reduces their service life.